复制代码 代码如下:

-判断某些字段是否为空

--case

select case when '字段名' is null then 'N' else convert(varchar(20),'字段名') end as 'NewName'

select case when null is null then 'N' else convert(varchar(20),null) end as 'NewName'

--SQL Server 2005：coalesce

select coalesce('字符串类型字段','N') as 'NewName'

select coalesce(convert(varchar(20),'非字符串类型字段'),'N') as 'NewName'

select coalesce(convert(varchar(20),null),'N') as 'NewName'

--coalesce,返回其参数中的第一个非空表达式

select Coalesce(null,null,1,2,null)union

select Coalesce(null,11,12,13,null)union

select Coalesce(111,112,113,114,null)